Prior to this invention various types of air heating units have been proposed for fireplaces. Some, such as the one shown in U.S. Pat. No. 4,062,344, are of relatively complicated construction and are not suitable for installation in an existing fireplace.
Others are of simplified construction and are adapted for placement in an existing fireplace recess without requiring modification to the fireplace structure. The simpler heating units, which can be placed on the floor of the fireplace, usually have a row or bank of log-supporting tubes and an electrically powered blower which forces air through the tubes by way of a manifold. The tubes are curved to pass above the fire so that the air is heated as it flows through the tubes. This type of forced air heating unit, while being relatively inexpensive, has several drawbacks.
For example, the air tubes are subject to heat damage if the electric power for operating the forced air blower is cut off for a significant length of time. Furthermore, this type of heating unit is usually designed to burn logs or the like and not other fuels such as stove coal. Still further, the burning of the fuel is no more efficient than it would be in the fireplace itself.
The present invention has none of the drawbacks mentioned above, but retains the advantageous feature of being easily installable in an existing fireplace as well as offering additional advantages as will become apparent from the following summary and detailed description.